Multiple material driver-type golf club head

ABSTRACT

A driver-type golf club head having a composite crown is disclosed herein. The driver-type golf club head includes a subassembly including a cast face component and a stamped sole component, and a compression molded crown component which is bonded to the subassembly. Each of the subassembly and the crown component has a non-overlapping bonding flange that bonds with an interior surface.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/119,997, filed on Dec. 4, 2008.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for a multiple materialdriver-type golf club head.

2. Description of the Related Art

The prior art discloses several methods for forming a golf club head.

One method is full casting which involves casting the entire golf clubhead, usually with a face pull tool. Duquette et al., U.S. Pat. No.6,978,976 for a Magnetized Core With Pneumatic Release System ForCreating A Wax Mold For A Golf Club Head describes certain aspects ofthe full casting method. Then a face insert is welded to the golf clubhead.

Another method is using a full casting method, using a face pull tooland then cutting a crown opening. A graphite crown is then bonded tocover the opening thereby forming a multiple material golf club head.

Yet another method is forming an entire golf club head from multiplepieces. In this method, several pieces (crown, sole, face and hosel) arewelded together to form a precursor golf club head. Then, an opening iscut in the crown creating an opening. A graphite crown is then bonded tocover the opening thereby forming a multiple material golf club head.

Yet another method is a high performance multiple piece golf club head.This forming method involves making a multiple piece golf club head. Thecrown material needs to be of high quality expensive titanium so priorto welding the crown component to the sole component, the crown ischemically milled to the limits of drop tower durability. The chemicalmilling process is necessary to render the crown component to becompetitive with graphite strength to weight ratio.

The current construction includes tacking a face component to sole(called face subassembly). Manually trim and tack crown to facesubassembly. Fully weld face, crown, and sole (21 inches of weld). Grindweld and polish head.

Each of these prior art methods have drawbacks. Both multiple piecegraphite crown and full casting require the manufacturer to produce acomplete golf club head. The crown opening is then cut and replaced witha graphite crown. This is obviously wasteful because of the need tofabricate an entire golf club head and then removing a portion. The highperformance multiple piece golf club head remedies this wastefulness byutilizing an expensive titanium material and which adds more cost torender the crown component weight competitive to graphite crowns.

BRIEF SUMMARY OF THE INVENTION

The present invention seeks to reduce the waste from current blacktopmanufacturing methods while achieving similar or better performance thanthe high performance multiple piece golf club heads at a price pointthat is similar to conventional multiple piece golf club heads.

The process includes a face component and a stamped metal sole componentpreferably welded together without a crown component. The face componentand the sole component are preferably welded together with a hightolerance. The face components and sole components are preferablymanufactured past “desired points” and trimmed back to match ‘net’ CADdesigns. The face component and the sole component weld line is thenpolished. This weld line is approximately six inches in length for a 460cubic centimeter volume driver-type golf club head. In prior artmultiple piece golf club head construction methods the weld line istypically twenty-one inches in length or more for a 460 cubic centimetervolume driver-type golf club head.

Thus, the present invention results in a significant reduction infinishing costs. More specifically, the finishing process for weldpolishing requires expensive polishing belts. There are approximatelyfive different belts ranging from very coarse to very fine. Each beltcan usually polish around four to five golf club heads.

In the present invention a crown is bonded to the golf club headsubassembly.

The resulting weight of the crown in carbon composite ranges from 15grams to 35 grams, more preferably from 20 grams to 30 grams and is mostpreferably 24 grams. The weight of the crown in the high performancemulti-piece of the prior art is approximately 31 grams. By using themethod of construction of the present invention, a manufacturer obtainsat least an additional seven grams of discretionary weight that can beused in other sections of the golf club head to improve mass propertiessuch as moment of inertias (Izz, Iyy and Izz) through the center ofgravity of the golf club head, durability (thicker face regions or otherregions open to stress during loading), and lower positioning of thecenter of gravity by shifting the mass of the golf club head.

The process for forming a driver-type golf club head includes weldingthe face component to the sole component to create a golf club headsubassembly. This comprises only six inches of welding as opposed to theprior art twenty-one inches of welding. The golf club head subassemblyis ground and polished, specifically the six inches of weld. The crowncomponent is glued to the golf club head subassembly to create anunfinished golf club head. The unfinished golf club head is cleaned andfinished.

This present invention is unique from other composite crown golf clubheads or high performance multi-piece construction golf club headsbecause material is not wasted beyond what is necessary to form the golfclub head. In traditional composite crown golf club heads, the wholegolf club head is formed (either by casting or welding) and then anopening is cut from this whole golf club head for the composite crown.In the high performance multi-piece construction golf club heads, thecrown component material is very expensive relative to conventionalstamped or cast materials, and this high performance multi-piececonstruction golf club head crown component material needs to bechemically milled to achieve its performance. The cutting and chemicalmilling wastes material and adds cost to achieve performance. The methodof the present invention achieves the same performance without addingadditional costs.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of an unfinished golf club head.

FIG. 2 is a side view of an unfinished golf club head.

FIG. 3 is a bottom perspective view of an unfinished golf club headillustrating the weld line to be polished.

FIG. 4 is an isolated top perspective view of an interior of asubassembly of a golf club head to illustrate the bonding flange of aface component.

FIG. 5 is an isolated front perspective view of a crown component of agolf club head illustrating the bonding flange of the crown component.

FIG. 6 is an enlarged isolated view of a crown component of FIG. 5illustrating the bonding flange and joint for bonding with thesubassembly.

FIG. 7 is a cross-sectional view of a bonding joint of a golf club headillustrating a bonding flange of the face component and the crowncomponent.

FIG. 8 is a cross-sectional view of a bonding joint of a golf club headillustrating a bonding flange of a crown component and a sole component.

FIG. 9 is a flow chart of the method of forming a driver-type golf clubhead of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The driver-type golf club head is formed by a process that preferablyincludes the manufacture of a cast face component 10 and a stamped metalsole component 18. The face component 10 and the sole component 18 areassembled together in a welding fixture. The welding fixture locates onthe inside of the face component 10 and inside of the sole component 18.The welding fixture also locates on some sections of the outsidesurfaces of the face component 10 and the sole component 18. The crowncomponent 16 is preferably formed from a carbon composite. Once the facecomponent 10 and sole component 18 are welded into a golf club headsubassembly, the golf club head subassembly is polished and prepared foradhesive bonding. The composite crown is bonded to the golf club headsubassembly using an adhesive. After the adhesive cures, the unfinishedgolf club head is cleaned and finished (typically painting).

Preferably the face component 10 is cast from titanium 6-4 alloy. Theface component 10 has a bonding flange 11 along the top of the facecomponent 10 extending about 0.200 inch below the OML parting line.Preferably the sole component 18 is a stamped titanium alloy. Thethickness of the sheet material for the sole component 18 is determinedby performance needs and manufacturability. The sole component 18 istrimmed. Preferably the crown component 16 is formed by compressionmolding a sheet molding compound. The crown component 16 has a bondingflange 17 between itself and the sole 18. Because of this designfeature, the compression molded manufacturing technique is a preferredmanufacturing technique. Alternative forming techniques includecontinuous fiber laminate construction and plastic injection molding.

As shown in FIGS. 1-8, a golf club head 20 is composed of a facecomponent 10 with a bonding flange 11, a sole component 18 and a crowncomponent 16 with a bonding flange 17 in order to construct the golfclub head 20 according to a method of the present invention.

In one example, the face component section 10 comprises a striking platesection 12 and a return section 14 extending rearward from a perimeterof the striking plate section 12. The return section 14 has a bondingflange 19 formed as an undercut extending rearward approximately 0.200inch from a top rearward edge of the return section 14. The subassemblyis composed of a titanium alloy material and comprises at least 70% ofthe mass of the golf club head 20.

The crown component 16 is composed of a compression molded graphitematerial. The crown component 16 has a top section and a bonding flange17 substantially perpendicular to the top section. The bonding forms anundercut relative to an edge of the top section.

The crown component 16 is adhesively bonded to the subassembly with aninterior surface of a front portion of the top section of the crowncomponent 16 bonded to an exterior surface of the bonding flange 19 ofthe return section 14 of the face component 10 of the subassembly. Anexterior surface of the bonding flange 17 of the crown component 16 isbonded to an interior surface of a portion of the sole component 18 ofthe subassembly.

In one embodiment, the golf club head 20 has a loft angle of at leastthirteen degrees. In a preferred embodiment, the fairway-wood type golfclub head has a volume of 460 cubic centimeters. The subassembly mayfurther comprise a hosel 22, which may be interior or exterior.

In another example, the subassembly comprises a sole component 18 and aface component 10 with a bonding flange 19 formed as an undercutextending rearward. The crown component 16 has a top section and abonding flange 17 substantially perpendicular to the top section. Thebonding is formed as an undercut relative to an edge of the top section.

The crown component 16 is bonded to the subassembly with an interiorsurface of a front portion of the top section of the crown component 16bonded to an exterior surface of the bonding flange 19 of the facecomponent 10 of the subassembly. Also, the exterior surface of thebonding flange 17 of the crown component 16 is bonded to an interiorsurface of a portion of the sole component 18 of the subassembly. Thesubassembly may be composed of a titanium alloy material or a stainlesssteel material. In one embodiment, the crown component is composed of anon-metal material.

A method for forming a golf club head 20 is illustrated in FIG. 9 andgenerally designated 100. At block 101, a face component 10 is cast. Atblock 102, a sole component 18 is stamped from metal, preferablytitanium. At block 103, the face component 10 and sole component 18 areassembled, preferably through welding, into a subassembly. At block 104,the weld line of the subassembly is polished. At block 105, a crowncomponent 16 is compression molded from a graphite compound. At block106, the crown component 16 is adhesively bonded to the subassembly. Atblock 107, the golf club head 20 is finished.

Variable face thickness patterns of the striking plate insert aredisclosed in U.S. Pat. No. 6,471,603, for a Contoured Golf Club Face,U.S. Pat. No. 6,368,234 for a Golf Club Striking Plate Having EllipticalRegions Of Thickness, U.S. Pat. No. 6,398,666 for a Golf Club StrikingPlate With Variable Thickness, U.S. Pat. No. 7,448,960, for a Golf ClubHead With Face Thickness which are all owned by Callaway Golf Companyand which pertinent parts related to the face pattern are herebyincorporated by reference.

The present invention is directed at a golf club head that has a highcoefficient of restitution thereby enabling for greater distance of agolf ball hit with the golf club head of the present invention. Thecoefficient of restitution (also referred to herein as “COR”) isdetermined by the following equation:

$e = \frac{v_{2} - v_{1}}{U_{1} - U_{2}}$

wherein U₁ is the club head velocity prior to impact; U₂ is the golfball velocity prior to impact which is zero; v₁ is the club headvelocity just after separation of the golf ball from the face of theclub head; v₂ is the golf ball velocity just after separation of thegolf ball from the face of the club head; and e is the coefficient ofrestitution between the golf ball and the club face.

The values of e are limited between zero and 1.0 for systems with noenergy addition. The coefficient of restitution, e, for a material suchas a soft clay or putty would be near zero, while for a perfectlyelastic material, where no energy is lost as a result of deformation,the value of e would be 1.0. The present invention provides a club headhaving a coefficient of restitution ranging from 0.81 to 0.94, asmeasured under conventional test conditions.

The mass of the club head of the present invention ranges from 165 gramsto 250 grams, preferably ranges from 175 grams to 230 grams, and mostpreferably from 190 grams to 205 grams. Preferably, the subassemblypreferably has a mass ranging from 140 grams to 200 grams, morepreferably ranging from 150 grams to 180 grams, yet more preferably from155 grams to 166 grams, and most preferably 161 grams. The crowncomponent has a mass preferably ranging from 4 grams to 20 grams, morepreferably from 5 grams to 15 grams, and most preferably 7 grams.

The golf club head preferably has a volume that ranges from 290 cubiccentimeters to 600 cubic centimeters, and more preferably ranges from330 cubic centimeters to 510 cubic centimeters, even more preferably 350cubic centimeters to 495 cubic centimeters, and most preferably 415cubic centimeters or 460 cubic centimeters.

The axes of inertia are designated X, Y and Z. The X axis extends fromthe striking plate insert through the center of gravity, CG, and to therear of the golf club head. The Y axis extends from the toe end of thegolf club head through the center of gravity, CG, and to the heel end 66of the golf club head. The Z axis extends from the crown section throughthe center of gravity, CG, and to the sole section.

As defined in Golf Club Design, Fitting, Alteration & Repair, 4^(th)Edition, by Ralph Maltby, the center of gravity, or center of mass, ofthe golf club head is a point inside of the club head determined by thevertical intersection of two or more points where the club head balanceswhen suspended. A more thorough explanation of this definition of thecenter of gravity is provided in Golf Club Design, Fitting, Alteration &Repair.

The center of gravity and the moment of inertia of a golf club head arepreferably measured using a test frame (X^(T), Y^(T), Z^(T)), and thentransformed to a head frame (X^(H), Y^(H), Z^(H)). The center of gravityof a golf club head may be obtained using a center of gravity tablehaving two weight scales thereon, as disclosed in U.S. Pat. No.6,607,452, entitled High Moment Of Inertia Composite Golf Club, andhereby incorporated by reference in its entirety.

In general, the moment of inertia, Izz, about the Z axis for the golfclub head preferably ranges from 2800 g-cm² to 5000 g-cm², preferablyfrom 3000 g-cm² to 4500 g-cm², and most preferably from 3750 g-cm² to4250 g-cm². The moment of inertia, Iyy, about the Y axis for the golfclub head preferably ranges from 1500 g-cm² to 4000 g-cm², preferablyfrom 2000 g-cm² to 3500 g-cm², and most preferably from 2400 g-cm² to2900 g-cm². The moment of inertia, Ixx, about the X axis for the golfclub head 40 preferably ranges from 1500 g-cm² to 4000 g-cm², preferablyfrom 2000 g-cm² to 3500 g-cm², and most preferably from 2500 g-cm² to3000 g-cm².

In general, the golf club head has products of inertia such as disclosedin U.S. Pat. No. 6,425,832, and is hereby incorporated by reference inits entirety. Preferably, each of the products of inertia, Ixy, Ixz andIyz, of the golf club head 40 have an absolute value less than 100grams-centimeter squared. Alternatively, the golf club head 40 has a atleast one or two products of inertia, Ixy, Ixz and Iyz, with an absolutevalue less than 100 grams-centimeter squared.

The width, W, preferably ranges from 4.0 inches to 5.5 inches, and mostpreferably from 4.75 inches to 5.0 inches. The height, H, preferablyranges from 2.0 inches to 3.0 inches, and most preferably ranges from2.40 inches to 2.65 inches. The length, L, preferably ranges from 3.5inches to 4.5 inches, and most preferably from 4.0 inches to 4.25inches. The golf club head 40 may have an aspect ratio such as disclosedin U.S. Pat. No. 6,338,683 for a Striking Plate For A Golf Club Head,assigned to Callaway Golf Company, and which pertinent parts are herebyincorporated by reference.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

1. A driver-type golf club head comprising: a subassembly comprising aface component and a sole component, the face component sectioncomprising a striking plate section and a return section extendingrearward from a perimeter of the striking plate section, the returnsection having a bonding flange formed as an undercut extending rearwardapproximately 0.200 inch from a top rearward edge of the return section,the subassembly composed of a titanium alloy material and comprising atleast 70% of the mass of the golf club head; a crown component composedof a compression molded graphite material, the crown component havingtop section and a bonding flanged substantially perpendicular to the topsection, the bonding formed as an undercut relative to an edge of thetop section; wherein the crown component is adhesively bonded to thesubassembly with an interior surface of a front portion of the topsection of the crown component bonded to an exterior surface of thebonding flange of the return section of the face component of thesubassembly and an exterior surface of the bonding flange of the crowncomponent bonded to an interior surface of a portion of the solecomponent of the subassembly.
 2. The driver-type golf club headaccording to claim 1 wherein the golf club head has a loft angle of atleast thirteen degrees.
 3. The driver-type golf club head according toclaim 1 wherein the fairway-wood type golf club head has a volume of 460cubic centimeters.
 4. The driver-type golf club head according to claim1 wherein the subassembly further comprises a hosel.
 5. The driver-typegolf club head according to claim 4 wherein the hosel is an exteriorhosel.
 6. The driver-type golf club head according to claim 4 whereinthe hosel is an interior hosel.
 7. A driver-type golf club headcomprising: a subassembly having a sole component and a face componentwith a bonding flange formed as an undercut extending rearward; a crowncomponent having top section and a bonding flanged substantiallyperpendicular to the top section, the bonding formed as an undercutrelative to an edge of the top section; wherein the crown component isbonded to the subassembly with an interior surface of a front portion ofthe top section of the crown component bonded to an exterior surface ofthe bonding flange of the face component of the subassembly and anexterior surface of the bonding flange of the crown component bonded toan interior surface of a portion of the sole component of thesubassembly.
 8. The driver-type golf club head according to claim 7wherein the subassembly is composed of a titanium alloy material.
 9. Thedriver-type golf club head according to claim 7 wherein the subassemblyis composed of a stainless steel material.
 10. The driver-type golf clubhead according to claim 7 wherein the crown component is composed of anon-metal material.